Metastatic brain cancer, also called secondary brain cancer, occurs when cancer spreads to the brain from another part of the body. It’s about ten times more common than primary brain cancer, which starts in the brain.

Each year, about 100,000 people in the United States are diagnosed with brain metastases. Approximately 20 to 40 percent of people with cancer develop this complication. More than half of them will have more than one tumor in the brain. The risk of a metastatic brain tumor depends on what kind of cancer you have and how advanced it is when it’s diagnosed.

In fact, more people than ever are being diagnosed with metastatic brain tumors. As we’ve gotten better at treating cancers, people with the disease are living longer. It’s therefore more likely their cancer will eventually spread. And improvements in imaging technologies allow us to see brain tissue in better detail, making it easier to spot abnormal areas.

The stage of your disease will determine your treatment. Your team may recommend surgery, radiation, or some combination of the two. At any point in your care you may also be eligible for a clinical trial exploring a new treatment option or approach.

Where in the brain do most metastases appear?

The cerebral cortex. This area is made up of the two large hemispheres of the brain, where high-level functions such as consciousness, memory, language, and sensory perception occur. Most metastatic brain tumors develop in the cerebral cortex.

The cerebellum. This is the part of the brain that oversees complex voluntary muscle movements. About 15 percent of metastatic brain tumors develop here.

The brain stem. About 5 percent of metastases develop in the brain stem, where visual coordination, swallowing, and balance are controlled.

Unknown primary origin. A small number of people develop brain metastases without doctors finding the primary cancer.